Sahih Bukhari Volume 5, Book 59, Hadith Number 537.

Narrated By Ibn ‘Umar : On the day of Khaibar, Allah’s Apostle divided (the war booty of Khaibar) with the ratio of two shares for the horse and one-share for the foot soldier. (The sub-narrator, Nafi’ explained this, saying, “If a man had a horse, he was given three shares and if he had no horse, then he was given one share.”)